Manufacture of contact fingers for electrical instruments



c. s. SNAVELYI MANUFACTURE OF CONTACT FINGERS FOR ELECTRICAL INSTRUMENTS.

APPLICATION FILED DEC- 8. 1916.

Patented Jan. 24, 1922.

INVENTOR WITNESSES V I UNITED, STATES PATENT OFFICE.

CLARENCE S. SNAVELY, OF WILKINSIBURG, PENNSYLVANIA, ASSIGNOR TO THE UNION SWITCH & SIGNAL COMPAN CORPORATION OF PENNSYLVANIA.

Y, OF-SWISSVALE, PENNSYLVANIA, A

IE ANUFACTURE 0F CON TACTFINGERS FOR ELEQTRICAL INSTRUMENTS.

Specification of Letters Patent.

Patented Jan. 24, 192 2.

Application filed December 8, 1916. Serial No. 135,800.

To all whom it may concern:

Beit known that I, CLARENCE S. SNAVELY, a citizen of the United States, residing at Wilkinsburg, in the county of Allegheny and State of Pennsylvania, have invented certain new and useful Improvements in Manufacture of Contact Fingers for Electrical Instruments, of which thefollowing is a specification.

This invention relates to electrical contacts, and more particularly to movable contact members having flexiblemetallic tips which engage with fixed contact members.

One feature of my invention is the pro vision of a method of, and means for, aligning the contact tips for proper engagement with the fixed contact member under the normal pressure, without the necessity for bending either the tips or the contact member itself.

In carrying out my invention, I provide a filing or grinding element, and means for pressing the flexible tip against the grinding element at a pressure corresponding to the pressure under which the tip is operated when engaging the fixed contact member, whereby the tip is automatically ground to form a true seat when contacting with the fixed contact member.

Other objects of the invention will appear from a consideration of the following detailed description, taken in connection with the accompanying drawings forming a part of this specification, with the understanding, however, that the embodiment illustrated, though practical, is by no means the only embodiment which theinvention may assume, wherefore the invention is not confined to' any strict conformity with the showing of the drawings, but may be changed and modified in various particulars, within the scope of the appended claims.

In the drawing is shown, in perspective, one form of apparatus embodying my invention.

Similar reference characters refer to similar parts in the drawing.

Referring to the drawing, my invention essentially consists of a grinding or filing means G and means W for causing a flexible tip T of a movable contact member C to bear with a predetermined pressure upon the grinding means, such pressure, corresponding to the pressure under which the tip is operated upon a relay when engaging a fixed contact member. As here shown, the grinding means G is in the form of a grindstone mounted for rotary movement upon a shaft S, while the pressure exerting means Wis here shown as a weight.-

. In this embodimentlof my-invention the contact member C is adjusted or aligned previous to the application thereof to an electrical apparatus or machine, such as an electromagnetic relay, although it is to be understood that a contact member may be aligned while in applied position by employing the grinding and pressure means here illustrated. The contact member C comprises a bar D and the tip T, the former being secured upon one end of a substantially horizontally disposed L shaped bracket B. The bracket B is pivotally mounted upon an axle A and is biased for downward swinging movement by means of the weight W, which is detachably secured to the bracket at its forward end, as shown.

From this construction and arrangement, it is evident that the weight W imparts downward pressure to the contact member C through the bracket B, and that by so doing the tip T is forced into engagement with the periphery of the grindstone G to be ground thereby in accordance with the pressure exerted by the weight W In view of the fact that the contact mem ber C is aligned before application to an electrical machine, the pivot of the bracket B and the active surface of the grindstone G, indicated as at X, are located in the same relation as the pivot point of contact member C and the working surface of a fixed contact member when the contact member 0 is in applied position, in order that the tip T be properly ground to a true seat upon the fixed contact member without necessitating bending or twisting. Consequently, when the grindstone is rotated, in the direction of the arrow, and the weight W applied to the bracket B, the tip T will be pressed upon the periphery of the grindstone at point X, with such force as to effectively grind the tip to a true seat.

Having described my invention, what I claim is:

1. Apparatus for grinding the contacting surface of a flexible Contact finger for electrical instruments, which fingeris attached to an operating member and co-acts with a. fixed contact member in the electrical in-.

strument said apparatus comprising a grinding member, means for mounting the operating member to move in the same path with relation to the grinding member as the path in which it moves with relation to the fixed contact member in the electrical instrument, and means for exerting onsaidi operating member the same force as is exertedthereon to close the contact in the electrical instrument, whereby said contact fingeris so ground that: when it is closed against the fix'edcontact member in the elec- V trical'instrument, it will present a fiat contacting surface to the latter memben 2. The method of grinding the contacting surface of a flexible contact finger for elecin presence oft-W0 witnesses.

. CLARENCE S. SNAVELY.

Witnesses A. HERMAN NVEGNER,

RUDOLPH G. RUDMAN. 

